skin disorder

My cat itches terribly and literally scratches big wounds open all around her neck and on her face. the vets have taken blood and taken skin tests for the microscope. there is no sign of an insect or mite or organism on her skin. its clear yet she itches. they put her on ovarid which worked well for a while but it has flared up again and the cortisone and ovarid no longer seems to have an affect.
i cant put her out just because of that but the wounds are relly getting bad. i have tried to bandage her which has also been very unsuccessful.
do you perhaps have any other ideas to help my cat

[Dr. Carol Osborne, DVM]

Organic oatmeal baths, distilled drinking water and a grain free diet are helpful for cat allergies.
Be sure you cat doesn't have fleas as the flea predilection site for cats is the head and neck area.
Chlorpheniramine maleate 4mg tablets are a mild cost effective antihistamine very helpful to relieve feline itching.

Dr Carol Osborne, DVM